Network Shares

I have got a minor problem here.

I am running W2k3 server as a DC and a file server

Everyhting has been fine all network drives are set up and running.

All of a sudden today one of the drives Z is showing in 'My Computer' as a disconnected network drive. When I click on it it is fine., but then when I return to 'My Computer' it still shows as disconnected.

To add insult other users are also experiencing the same with Z:

when I examined a user profile and tried to connect Z:// as a home folder, it came back and told me that Z:// was being used as a root share?